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Relatively new EE here with a quick question. You can, technically, make a system with the same output (spelling penis, etc.), without a microcontroller, correc

Relatively new EE here with a quick question. You can, technically, make a system with the same output (spelling penis, etc.), without a microcontroller, correct? With the proper frequency dividers, timers, and logic gates? Or am I wrong here?

kelvin0 12y ago
Of course, but then the instructor would have noticed the extra hardware and it would have ruined the fun ...
- TheLoneWolfling 12y ago
  Expert mode: Make the discrete-component circuit to do this inside the logic gate. (Especially hard as there are components that physically cannot be made small enough (large caps / inductors, etc))
  - wiml 12y ago
    Intermediate mode: You could program the discrete logic onto a tiny CPLD and probably still hide it inside the 74'193. That way you'd still technically be complying with the "no microcontrollers" constraint.
    - makomk 12y ago
      Sadly, it's probably a little hard to fit a CPLD in that kind of space without wire-bonding equipment. They also tend to lack the infernal clocks that most microcontrollers have these days.
snarfy 12y ago
I made a BLDC controller using TTL logic. It took about 15 chips. I could have made the same thing with a single 8 pin atiny85.
shawnz 12y ago
You could reproduce the whole microcontroller with just those things, if you wanted. So inherently the answer is yes. If you mean to ask if it can be done without software, the answer is still yes.
wiml 12y ago
Definitely. You could make a small hardwired state machine and decode its various states into the behavior you wanted, for example. It would probably take a dozen or so 7400-series logic chips (depending on how complex the easter-egg behavior is). That kind of small, non-microprogrammed machine is really common, but people don't build them out of discrete logic any more, or probably even design them by hand. They're written in VHDL or something, and synthesized into silicon or a gate array. They're how a programmable controller is implemented (something has to be under the bottom-most layer of microcode), but they're also used for lots of other little peripheral tasks. I'd guess the student in the article will be formally taught about them in another quarter or two.

kelvin0 12y ago

Of course, but then the instructor would have noticed the extra hardware and it would have ruined the fun ...

TheLoneWolfling 12y ago
Expert mode: Make the discrete-component circuit to do this inside the logic gate. (Especially hard as there are components that physically cannot be made small enough (large caps / inductors, etc))
- wiml 12y ago
  Intermediate mode: You could program the discrete logic onto a tiny CPLD and probably still hide it inside the 74'193. That way you'd still technically be complying with the "no microcontrollers" constraint.
  - makomk 12y ago
    Sadly, it's probably a little hard to fit a CPLD in that kind of space without wire-bonding equipment. They also tend to lack the infernal clocks that most microcontrollers have these days.

snarfy 12y ago

I made a BLDC controller using TTL logic. It took about 15 chips. I could have made the same thing with a single 8 pin atiny85.

shawnz 12y ago

You could reproduce the whole microcontroller with just those things, if you wanted. So inherently the answer is yes. If you mean to ask if it can be done without software, the answer is still yes.

wiml 12y ago

Definitely. You could make a small hardwired state machine and decode its various states into the behavior you wanted, for example. It would probably take a dozen or so 7400-series logic chips (depending on how complex the easter-egg behavior is). That kind of small, non-microprogrammed machine is really common, but people don't build them out of discrete logic any more, or probably even design them by hand. They're written in VHDL or something, and synthesized into silicon or a gate array. They're how a programmable controller is implemented (something has to be under the bottom-most layer of microcode), but they're also used for lots of other little peripheral tasks. I'd guess the student in the article will be formally taught about them in another quarter or two.